Water (H2O) has been often used for forming oxides in atomic layer deposition (ALD) processes. Water is a polar molecule due to its lone electron pair. Water is also reactive with many metal halides, which makes it a candidate for some ALD oxide processes. When used as a reactant at low temperatures, however, water has displayed some undesirable behavior.
Most notably, the presence of water as a reactant increases the time to sufficiently purge the tool during an ALD deposition cycle. Specifically, at low temperatures, water tends to stick to various surfaces, including substrates and tools with hydrophilic materials. The sticking of water may make it difficult to purge water from the system and it may cause loss of selectivity if water-based processes are applied on selective deposition schemes. In addition, the nature of water may oxidize some of the surfaces present on the substrate, which in some instances is not desirable.
Prior approaches have described using carboxylic acids for ALD of some metal oxides. However, these have not enabled selective deposition.
As a result, a method for ALD formation of a film that displays efficient purging and effective modification of the surface is desired.